Time delay mercury switch with gas equalization means



1965 YASUNOSUKE ISHIGURO 3,166,657

TIME DELAY MERCURY SWITCH WITH GAS EQUALIZATION MEANS Filed Aug. '7, 1961 FIG. 2.

INVENTOR YASUNOSURB ISHIGURO ATTORNEY 3,166,657 TIME DELAY MERCURY SWITCH WITH GAS EQUALIZATION -MEANS Yasuuosuke Ishiguro, 1,639 Nishi- Terao-Machi, V

Kanagawa-ku, Yokohama, Japan Filed Aug. 7, 1961, Ser. No. 129,618 Claims priority, application Japan, Aug. 22, 1960,

3 (Ilaims. (Cl. 200-122) electric heater element the heating of which expands the gas in the compartment thus altering the levels of the mercury in the compartments and making or breaking electrical contact between the switch terminals, the compartments being also connected by a gas passage which in use is closed by a plug.

An embodiment of the invention will be explained with reference to the accompanying drawings, in which FIGS. 1 and 2 are sectional elevations illustrating two embodiments of the time limit switch according to the invention.

Referring to the drawing, 1 represents a load circuit, E is its electric source, L a load, such as electric lamps. 2 represents a circuit for controlling a heating element comprising an electric source E a switch S and a variable resistance R. 1

According to the invention, an enclosed casing 3 made of an insulating material, such as, synthetic resin and the like is formed therein two compartments 4 and 5 and to the bottom of the compartment 4 is provided with two cavities 6 and 7 separated by the intermediate partition and each of these cavities is provided with conductors 8 and 9 respectively projected therein penetrating through the casing wall. The conductors 8 and 9 are connected to the terminal 1 and 1 respectively of a load circuit having the electric source E and load L.

One of the cavities 7 is connected through a passage 10 to the bottom cavity of the other compartment 5 and a definite quantity of mercury 11 and inert gas 12, such as, nitrogen are sealed in the compartments 4 and 5. In one of the compartment 5 is sealed an electric heating element 13, such as, electric resistance wire which is connected to the terminal rods which latter are connected to each end of a source circuit 2 including a source E a variable resistor R and a controlling switch S. The compartments 4 and 5 may be communicated through a hole 14 which is controlled by a plug for regulating the level of the mercury in each compartment.

The operation of the time limit switch of the invention constructed as above described will be explained in the following:

If the switch S in the source circuit 2 is closed the current from the source E passes through the electric element 13 to be heated, thus the inert gas 12 filled in the compartment 5 is gradually heated to expand and accordingly the pressure in the compartment 5 in which the electric heating element 13 is sealed is increased higher than that in the other compartment 4 so that the level of mercury in the compartment 5 is gradually lowered whilst the level of mercury in the other compartment 5 will be raised correspondingly.

The device shown in FIG. 1 is so constructed that the load circuit 1 is normally open, which is closed by the 3,166,657 Patented Jan. 19, 1965 ice operation of the time limit switch and accordingly in this case under a normal condition the upper levels of the mercury columns in the cavities 6 and 7 are located below the top of the partition wall so that these columns are not in contact with each other. Accordingly the load circuit 1 is open. But as above described it the switch S is closed and electric current passes through the electric Y heating element 13 to heat it and the pressure in the compartment 5 is raised to press down the mercury 11 so that the mercury in the cavity 7 is forced up. Thus after a definite time limit it is associated with mercury in the cavity 6. Thus when the mercury 11 in the cavities 6 and 7 is communicated the load circuit is closed through the conductors 8, 9 and. the mercury 11. On the contrary if the switch S is opened the electric heating element 13 is gradually cooled, then the pressure in the compartment 5 decreases correspondingly and the level of the mercury is brought back to the original position after a definite time limit so that the mercury in the cavities 6 and 7 is interrupted to open the load circuit 1 again.

The device as shown in FIG. 2 is that which is reversed type of that shown in FIG. 1, i.e. the load circuit is normally closed owing to the communication of the mercury in the cavities 6 and 7 as shown, and instead of the mechanical switch S use is made of an automatic circuit controlling element S, such as, a photo-electric conductor element, such as, cadmium sulphide, which becomes conductive when it is illuminated by light. Such device can be used as an automatic time limit control of lamp circuit for street illumination for automatically lighting the lamps at night and extinguishing them in the morning when the photo-electric conductor element S is illuminated by the external light.

In this case, as above described, when the pressure in the compartment 4 is increased due to heating of the electric heating element 13 the mercury in the compartment 4 is pressed down to disconnect the mercury in the cavities 6 and 7 so that the load circuit 1 is opened. Under such condition, if the circuit controlling element S in the source circuit 2 becomes non-conductive to stop the current to the heating element 13 the mercury returns to the original state after a definite time limit to reclose the load circuit 1 again.

The terminal rods 8 and 9 may be short-circuited by means of a condenser (not shown) for preventing the spark which might occur between the separating mercury columns as a conventional means.

The time when the load circuit 1 is closed or opened after the switch S in the source circuit 2 is closed or opened can be easily adjusted as desired by suitably regulating the variable resistance R or by suitably designing the constituting parts of the device. of the load circuit according to the present device is effected by means of mercury only so that the durability of the contact members is very elongated.

As apparent from the above description the device of the invention is very simple in construction and can be made compact, but has no tendency to cause faults and can operate positively for a long period so that it provides a large merit in various industrial purposes as it can be utilized broadly as time limit switches.

What I claim is:

1. A time delay switch for electrical circuits comprising a casing formed of insulator material, a first and second compartment formed in said casing, said compartments being filled with inert gas, a partition extending up wardly from the bottom of said first compartment to form a first and second cavity therein, said first compartment being provided with a constricted portion immediately above said partition, a first passage communicating between said first cavity and said second compart ment, said passage and said first and second cavities being The open and close "7) V ,3 filled with mercury, a first electrode extending through said housing into said first cavity and in electrical con tact with the mercury contained therein, a second electrode extending through said housing into said second cavity and in electrical"'contact'with the mercury contained therein, electrically actuated heater means to selectively heat the gas in one of said compartments to transfer mercury to the other compartment in response to operation of said heater, and a second passage communicating between said first and second compartments, a plug normallyrinserted in said passage to block said: passagepreventing gas transfer between compartments during operation of said switch and being selectively removable to open said passage for communicationbetween said first and second compartments to permit equalization of gas pressure. in said compartments.

2. A switch in accordance with claim l-inrwhich the mercury level in said first compartment is normally below the top. of said partition and, in which said heater is positioned in said second compartment to force mercury into I said first compartment on actuation of said heater thereby to raise the mercury level in said first compartment over said partition to couple said first and second electrodes together electrically.

3. A switch in accordance with claim 1 in which said heater is positioned in said first compartment and in which the mercury level in said compartment is normally above said partition so that actuation of said heater will transfer mercury to said second compartment, thereby to interrupt the coupling between said first and second electrode as the level falls below said partition.

1,231,221 'Trosda-hl June 26, 1917 1,614,621 McCabe 'Jan. 18, 1927 1,674,489 Vickery 'June19, 1928 e. 1-,980,243 v[Wordsall Nov. 13, 1934 2,046,416 Smith et a1. July 7, 1936 2,978,591 Ringger Apr. 4, 1961 FOREIGN PATENTS 763,666 France ..a May 4, 1934 

1. A TIME DELAY SWITCH FOR ELECTRICAL CIRCUITS COMPRISING A CASING FORMED OF INSULATOR MATERIAL, A FIRST AND SECOND COMPARTMENT FORMED IN SAID CASING, SAID COMPARTMENTS BEING FILLED WITH INERT GAS, A PARTITION EXTENDING UPWARDLY FROM THE BOTTOM OF SAID FIRST COMPARTMENT OF FORM A FIRST AND SECOND CAVITY THEREIN, SAID FIRST COMPARTMENT BEING PROVIDED WITH A CONSTRICTED PORTION IMMEDIATELY ABOVE SAID PARTITION, A FIRST PASSAGE COMMUNICATING BETWEEN SAID FIRST CAVITY AND SAID SECOND COMPARTMENT, SAID PASSAGE AND SAID FIRST AND SECOND CAVITIES BEING FILLED WITH MERCURY, A FIRST ELECTRODE EXTENDING THROUGH SAID HOUSING INTO SAID FIRST CAVITY AND IN ELECTRICAL CON6TACT WITH THE MERCURY CONTAINED THEREIN, A SECOND ELECTRODE EXTENDING THROUGH SAID HOUSING INTO SAID SECOND CAVITY AND IN ELECTRICAL CONTACT WITH THE MERCURY CONTAINED THEREIN, ELECTRICALLY ACUTATED HEATER MEANS TO SELECTIVELY HEAT THE GAS IN ONE SAID COMPARTMENTS TO TRANSFER MERCURY TO THE OTHER COMPARTMENT IN RESPONSE TO OPERATION OF SAID HEATER, AND A SECOND PASSAGE COMMUNICATING BETWEEN SAID FIRST AND SECOND COMPARTMENTS, A PLUG NORMALLY INSERTED IN SAID PASSAGE TO BLOCK SAID PASSAGE PREVENTING GAS TRANSFER BETWEEN COMPARTMENTS DURING OPERATION OF SAID SWITCH AND BEING SELECTIVELY REMOVABLE TO OPEN SAID PASSAGE FOR COMMUNICATION BETWEEN SAID FIRST AND SECOND COMPARTMENTS TO PERMIT EQUALIZATION OF GAS PRESSURE IN SAID COMPARTMENTS. 